CHARACTERIZATION OF LA-CROSSE VIRUS-RNA IN AUTOPSIED CENTRAL-NERVOUS-SYSTEM TISSUES

A reverse transcription-PCR (RT-PCR) technique was used to detect La C rosse (LAC) virus RNA in the central nervous system (CNS) tissues of t wo patients who died of LAC encephalitis in 1960 and 1978, Viral RNA w as readily detected by RT-PCR although the tissues had been stored fro zen for up to 37 years. LAC virus was detected in the cerebral cortex but not in other CNS tissues. RT-PCR allowed detection of replicative forms of the virus, indicating that the virus was actively replicating in the specific CNS tissues. The small (S) RNA segments of the viruse s from the CNS samples were demonstrated to be genetically similar by single-strand conformation polymorphism analyses. These S RNA segments were then sequenced; only two base changes were demonstrated between the 1960 and the 1978 samples, suggesting that LAC virus is geneticall y stable in areas of endemicity, The RT-PCR analyses of analyte direct ly from CNS tissues allows study of the virus without passage in cell culture.